Liquid Nitrogen
Liquid Nitrogen
(OP)
Greetings,
we have two storage tanks of liquid nitrogen as an emergency back-up in our plant, and it was written in the vendor manual the storage capacity can supply the required nitrogen in a gaseous form for 8 hours with flow rate of 9000 SCFM and 24 hours with flow rate of 1300 SCFM. however, if you try to calculate it reversibly you will find different capacity values.
tank capacity= 53 m3 (we have two).
- for sure the volume of liquid nitrogen is different than the nitrogen gas but it shouldn’t be different when you calculate it back , and i have used the expansion factor 694 m3 of gas for each 1 m3 of liquid nitrogen ? is this expansion factor right ?
- what is the conversion factor to convert from m3 to SCF of liquid nitrogen?
Regards,
we have two storage tanks of liquid nitrogen as an emergency back-up in our plant, and it was written in the vendor manual the storage capacity can supply the required nitrogen in a gaseous form for 8 hours with flow rate of 9000 SCFM and 24 hours with flow rate of 1300 SCFM. however, if you try to calculate it reversibly you will find different capacity values.
tank capacity= 53 m3 (we have two).
- for sure the volume of liquid nitrogen is different than the nitrogen gas but it shouldn’t be different when you calculate it back , and i have used the expansion factor 694 m3 of gas for each 1 m3 of liquid nitrogen ? is this expansion factor right ?
- what is the conversion factor to convert from m3 to SCF of liquid nitrogen?
Regards,





RE: Liquid Nitrogen
What conditions are considered for "S"? 70 deg F, 1 atm / 0 deg C, 1 atm / 15 deg C, 1 atm, or something else?
expansion factor would be dependent on what temperature / pressure you are expanding to?
9000 SCFM is pretty big, i'm assuming it's being pumped?
RE: Liquid Nitrogen
What conditions are considered for "S"? 70 deg F, 1 atm / 0 deg C, 1 atm / 15 deg C, 1 atm, or something else? i don't know the vendor calculation basis
expansion factor would be dependent on what temperature / pressure you are expanding to? 113 F ( ambiant) and 160 psig.
9000 SCFM is pretty big, i'm assuming it's being pumped? its downstream the ambian vaporizers
RE: Liquid Nitrogen
Who knows? We don't. All depends on what the specification called for and then the vendor has taken the worst case scenario to size the tanks.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Liquid Nitrogen
Thanks,
RE: Liquid Nitrogen
I got confused by the change in units. It actually works out quite well when you use 9000 sm3H...
Using the right units and your ~ 700:1 gas/liquid ratio, I agree your figures don't work.
however on a SCF basis, scenario A = 4.32 MMscf, scenario B = 1.87 MMscf
Turning this into m3 liquid This handy little site http://www.airproducts.com/products/Gases/gas-fact...
gives 1.3MMscf for 53,000 litres of liquid N2, so 2.6MMscf for 106 m3 liquid N2. so scenario B works, but scenario A doesn't
Something's not right, but what it is I can't tell from here.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Liquid Nitrogen
RE: Liquid Nitrogen
Scenario B has capacity for 33.4 hrs at 1,300 scfm.
RE: Liquid Nitrogen
Until ALL of the liquid has evaporated into gas, the 1:700 liquid-to-gas volume ratio is going to dominate, right?
RE: Liquid Nitrogen
-yes, right
thanks
RE: Liquid Nitrogen
RE: Liquid Nitrogen
RE: Liquid Nitrogen
RE: Liquid Nitrogen
RE: Liquid Nitrogen
You are running the 24 hour units at less than a quarter of the 8 hour flowrate which is quite the derating - I'm assuming it is quite a high fin density on the units?
Do you have datasheets for the ambient vaporisers? Could you not just contact the company directly?
RE: Liquid Nitrogen
Yes, I have contacted the company and I did not receive any feedback yet
RE: Liquid Nitrogen
RE: Liquid Nitrogen
So these rates need not both match up with the emergency LN2 tank inventory. One of these may while the other need not, or maybe neither do.
RE: Liquid Nitrogen